3.3.3. CONNECTION OF RS485(2-WIRE) DEVICES
Most of RS485 devices use 2-wire RS485 network for data transmission.
Example of connection ADA-1040 to 2-wire RS485 network (multipoint topology) is shown below.
Fig 9. Connection to RS485(2W) devices
3.3.4. EXTENSION OF RS232 PORT
Example connection of two ADA1040 in purpose of extend the signals Tx, Rx, DTR, DSR of RS232 computer port, is shown below.
Fig 10. RS232 Extension type connection
3.3.5. GND TERMINAL CONNECTION
Connection of GND terminals of RS485/422 interfaces, devices connected to RS485/422 bus, should be done in the case of a
potential difference of the signals grounds on interfaces RS485 / RS422, which prevents proper data transmission.
Cannot connect to the GND terminal - cables screens, PE circuit of electrical installation, signals grounds of other devices.
3.3.6. LINE TERMINATION
The application of Line Termination (terminator) Rt = 120 ohms will reduce electrical reflection in data line at high baud rate. It is not
needed below 9600Bd. The Line Termination resistor should be used if the distance is over 1000m @ 9600Bd or 700m @ 19200Bd
transmission, the resistor can be necessary if there are problems with the transmission correctness. The terminators/resistors are
connected to the terminal block of ADA-1040 on the RS485/RS422 interface. Example connection of Rt are shown on Fig. 7, 8 & 9.
8
ADA-1040
ADA-1040
RS485/422
terminal
Vss+
Vss-
Power
Supply
RS232
connector
Vss-
Vss+
Tx+/A
Tx-/B
Rx+
Rx-
Rt
CTS -7
RTS -8
GND -5
Tx -2
Rx -3
DSR -4
DTR -6
RS485(2W) Network
1200m
1200m Network
RS485(4W)/RS422
4-pair twisted cab.
RxD - 2
TxD - 3
DTR - 4
DSR - 6
RTS - 7
CTS - 8
PC
SG -5
RS232 port
DTE/DB-9M
ADA-1040
RS485/422
connector
Vss+
Vss-
Power
Supply
RS232
DCE/DB-9F
CTS -7
RTS -8
GND -5
Vss-
Vss+
Tx -2
Rx -3
DSR -4
DTR -6
Tx +
Tx -
Rx +
2
3
4
6
7
8
5
CAB-DB 9F/DB9M-S-1,8m
cable
DB-9F
socket
2
3
4
6
7
8
5
DB-9M
plug
Rx -
DTR +
DTR -
DSR +
DSR -
ADA-1040
RS485/422
connector
Vss+
Vss-
Power
Supply
RS232
DCE/DB-9F
CTS -7
RTS -8
GND -5
Vss-
Vss+
Tx -2
Rx -3
DSR -4
DTR -6
Tx +
Tx -
Rx +
Rx -
DTR +
DTR -
DSR +
DSR -
2
3
4
6
7
8
5
Cable / Adapter
CAB-DB9M/BD9M-C-2m /
ADP-DB9M/DB9M-C
DB-9F
socket
2
3
4
6
7
8
5
DB-9M
plug
